Chang'an is the starting point of "Silk Roads: the Routes Network of Chang'an-Tianshan Corridor", which was listed as World Heritage in 2014. Based on the practice and exploration of presentation of the Chang'an City Site of Tang Dynasty in Xi'an, this paper presents a discussion of how to combine the interpretation of cultural routes with the interpretation and presentation of the urban traces under a modern city. Under the pressure of urban development and renewal, it explores the interpretation strategies based on cultural routes, trying to solve the contradictions between the needs of potential heritage conservation and urban development. Moreover, the paper explores contradictions between meanings and values arising among approaches to heritage sites in relation to the urban role as a starting point of the Silk Road. Focusing on the need to actively integrate potential underground ruins into the development plan of the city, the paper extends the notion of "setting" to include the historic urban context and their structuring components. Integrating archaeological and literature materials and based on the heritage value of Chang'an City of Tang Dynasty in the cultural route, the paper attempts to sort out the relationship of inheritance and continuity between the underground city and the modern city patterns. It is argued that such kind of sorting is a key task for spatial interpretation. Furthermore, the spatial interpretation-based strategy for potential sites is recommended as the tool to explore the guiding principles of urban cultural heritage interpretation and land use co-development.